Our brain's response to the word "radioactivity" usually takes us into the world of superheroes,
or into some dark reimagined post-apocalyptic world after a nuclear fallout.
There is rarely middle ground. However, 120 years ago, the world
had a completely different perception of radioactivity. In fact, it was considered
to be a miraculous reservoir of health and vitality. From toothpaste and watch dials to
water and butter—radioactivity was everywhere. So, what happened? How has this marvelous
discovery, which was considered one of humankind's greatest achievements, turned into something that
scares countless people across the globe? Let’s start with the basics.
Everything we see around us is composed of elements with stable atoms. The subatomic
component responsible for maintaining the stability of an atom is called the nucleus.
Now, imagine that you’re about to sneeze, but it hasn’t quite come out yet. How does that feel?
It might be strange to describe, but that’s exactly what certain atoms experience
all the time—the urge to expel the excess and regain stability.
Inside an atom’s nucleus, there are positively charged protons and neutral neutrons. These
nucleons are held together by a “glue” called the strong nuclear force. This strong force cancels
out the repulsive electrostatic force of like charged protons and keeps the nucleus stable.
The nuclear force has a short range of action and is dependent on the ratio of
neutrons and protons present in a nucleus. However, we see that the balance between
the forces starts to waver in a nucleus where the number of neutrons exceeds the number of protons.
A nucleus that exceeds the threshold number of neutrons and protons
that the strong nuclear force can hold together comfortably will be more unstable.
More specifically, these scenarios give rise to unstable isotopes of elements.
Just as your body, through a series of expansions and contractions, expels a substance with
a sneeze, similarly, the unstable isotopes of elements fling out different particles or forms
of energy to restore balance between the forces in their nucleus. During this process of attaining
stability, they change into a new nucleus. It is exactly this property,
namely turning into something new to attain stability, that we call radioactivity.
The process by which it transforms is called radioactive decay.
A nucleus can undergo nuclear or radioactive decay through the emission of alpha, beta,
or gamma radiation (and sometimes a combination of all three).
The alpha particles are relatively heavy. They can travel only a few centimeters in the air and can
be easily stopped by a sheet of paper or plastic. Beta particles have higher energy and more
penetrating power than alpha particles, but are less ionizing in nature. They can travel
through the air, but can be stopped by a thin sheet of metal or even protective clothing.
Finally, the most energetic and fatal form of radioactive decay: Gamma rays - yes, the type
that supposedly turned Bruce Banner into The Hulk. This is a form of high-energy light emitted by a
nucleus that is left at a higher energy state after an alpha and beta decay process and must
return to a more stable lower energy state. A nucleus can undergo all of these decays
spontaneously and transform into a stable form within seconds, years or even centuries!
This rate of decay is decided by what we refer to as the “half-life” of the radioactive substance,
which measures the time it takes for a given amount of the substance to become
reduced by half as a consequence of decay. One cannot have a discussion regarding
radioactivity without a mention of the famous scientist Marie Curie.
Her lead-sealed radioactive laboratory, notebooks, cookbooks, and furniture contaminated by radium
are a testimony to her contributions to the field. She is also the only person to win
the Nobel Prize in both Physics and Chemistry. The discovery of radioactivity and radioactive
elements came through Marie and Pierre Curie, along with Henri Becquerel, in the early 1900s,
opening up the gates to a completely new field of atomic physics.
That eventually led to the discovery of different components of atoms and nuclear energy.
For example, radioactive elements like Uranium-235 and Plutonium-239, when bombarded with neutrons,
release an enormous amount of energy. When properly manipulated inside a nuclear reactor,
these fuels can act as massive and prolonged sources of energy.
Believe it or not, just one kilogram of Uranium-235 can produce almost 24 million
kWh of power by nuclear fission. In comparison, 1 kg of coal can only produce 8kWh of energy.
This is why it has been said that nuclear energy can power entire cities for decades.
Needless to say, the sheer power and potential of carefully handled radioactivity and nuclear
energy is immense. But, as is true with all great things, radioactivity also comes with some risks.
Radiation as a whole isn’t dangerous. Light bouncing off a reflective surface,
the microwaves heating our food, or the signals received by our mobile phones are all different
forms of radiation. However, there is one kind of radiation that is particularly harmful to all
biological forms: ionizing or nuclear radiation. A radioactive material during its decay process
emits ionizing radiation, and when a living being is exposed to such high-energy radiation,
it doesn’t make someone radioactive, but rather a likely victim of radiation poisoning.
Radiation poisoning from nuclear radiation can easily damage the molecular structure of DNA
and harm living cells. A heavy or prolonged dose can prove lethal,
as these rays are carcinogenic. Uranium, a very common fuel used
in nuclear reactors all over the world, when ingested, primarily attacks and
damages the kidneys. A prolonged exposure or heavy dose usually results in death.
What happened at the Chernobyl reactor decades ago has left mankind shaken to this day. One incident
of a reactor meltdown and four square miles of land are rendered uninhabitable for generations,
not to mention the thousands of lives exposed to the indelible effects of radiation poisoning.
The authorities have built a sarcophagus of concrete around the plant to prevent
the leaking of additional radiation into the atmosphere. The remains of the reactor sit inside
a containment structure made of thick steel walls. Clean-up protocols will be continued until 2065.
The Fukushima Daiichi reactor that was hit by a tsunami in 2011 forced the evacuation of thousands
in a 20km radius of the incident. The authorities are still cleaning up its surroundings,
including removing and disposing of the topsoil in the affected region.
Although it may seem that the word “radioactive” has a negative connotation,
surprisingly, radioactivity is not always harmful.
There is a saying in toxicology that “the dose makes the poison.”
It’s true that when a person is exposed to unregulated amounts of radioactive material,
it can cause severe genetic mutations and cancer.
However, when regulated, it can also cure cancer.
Radioactive iodine is used in radiation therapy to treat cancer and for imaging in the thyroid
gland. Radioactive technetium is used for the detection of heart, bone, and other organ defects.
Radioactive C-14 carbon is used in carbon dating which helps us determine the age of
things, specifically things that are younger than 50-60,000 years old. In some countries,
fresh produce is lightly irradiated before packaging to kill off the germs on the surface
of fruits and vegetables. A tiny amount of Americium-241 is used in smoke alarms
that help save thousands of lives every year. Mankind and radioactivity have coexisted
peacefully for ages. The air we breathe, the bananas we so add to our smoothies,
and the exit signs that lead the way all contain radioactive elements, but in safe amounts.
Quite simply, radioactivity is everywhere, but hypothetically, if you end up backpacking to
an unknown land and the Geiger counter in your bag and starts crackling, the best thing to do is run!